Method and apparatus for preheating can body side seams



Dec. 31, 1957 LE ROY o. BLUME METHOD AND APPARATUS FOR PREHEATING CANBODY SIDE SEAMS Filed Aug. 11, 1955 2 Sheets-Sheet 1 WO N N b m w b I In I I I u v In MH A w ww m V A z 0 a m. .e L

ATTORNEYS Dec. 31, 1957 LE ROY o. BLUME METHOD AND APPARATUS FOR FREE-EATING CAN BODY SIDE SEAMS 2 Sheets-Sheet 2 Filed Aug. 11, 1955 A'BYdim/0 METHOD AND APPARATUS FOR PREHEATING CAN BODY SIDE SEAMS LeRoy 0.Blume, Chicago, 111., assignor to Continental Can Company, Inc., NewYork, N. Y., a corporation of New York Application August 11, 1955,Serial No. 527,830

Claims. (CI. 219-1041) The invention relates generally tov canmanufacture and more specifically to the, making of can bodies havingsoldered side seams of any of the various types known to the industry.Before such side seams are solder bonded it is desirable to preheat themto a hig degree in order to facilitate efficient introduction of thebonding solder into the side seam structures, and the present inventionseeks to provide a new and improved method of and apparatus foraccomplishing such preheating.

One object of the invention has been to utilize a conventional form ofhigh frequency generator in bringing about the application of therequired heat to the side seams. Such generators are commonly used witha high frequency coil for heating a work-piece which is to be soldered,brazed or welded. Heat is not conducted or radiated from the highfrequency coil to the work-piece to accomplish the desired heating ofthe latter and in fact the coil is commonly water-cooled. On thecontrary, the heating is accomplished by the action of the magneticfield created by the coil, Therefore, the provision of a high frequencycoil which would create a magnetic field of such form as to be capableof effective concentration and localization on can body side seams, hasbeen a most importantobject of the invention. This object has beenattained by the provision of a high frequency coil having an elongatedreach which creates a correspondingly elongated tubular magnetic fieldaround itself. Thus, an apparatus and method are made possible, whereinthe can bodies with their side seams aligned, are fed and guided along apath unidirectional with the elongated coil reach, and the side seamsare maintained within the tubular magnetic field during the travel ofthe can bodies along said path. In this manner the action of the tubularmagnetic field will be eonoentrated and localized on the seam portionsof the can bodies where required, to produce the concentrated heatingpreparatory to solder-bonding.

The preferred high frequency coil is formed from copper tubing of about5 diameter. This coil comprises the aforesaid elongated reach, inrectilinear form, two return bends, one at each end of said elongatedreach, two relatively short aligned reaches paralleling the elongatedreach and extending inwardly toward each other from said return bends,and two terminal portions laterally bent from the adjacent ends of saidrelatively short reaches and extending away from said elongatedrectilinear reach. Only the magnetic field surrounding the elongatedrectilinear reach is utilized for heating the can body side seems and ithas been found that the best results are obtained when this reach isabout 6' long, with its longitudinal center spaced about 2 /1" from thelongitudinal center of the relatively short reaches. This specific coilconstruction has well attained the desired ends and has made possiblethe heating in one second and to a highly adequate temperature, the sidewarns of can bodies travelling at a rate of 600 per minute.

Another object has been to make novel provision to insure that the, canbody guiding means. shall have no 2,818,483 Patented Dec. 31, 1957 "iceharmful effect upon the magnetic field created around the effectivereach of the high frequency coil.

With the above and other objects in view that will hereinafter appear,the nature of the invention will be more clearly understood by referenceto the following detailed description, the appended claims and theseveral views illustrated in the accompanying drawings.

in the drawings:

Figure l of the accompanying drawings is a somewhat diagrammatic topplan view illustrating the invention.

Figure 2 is an enlarged transverse sectional view illustrating a canbody passing over the seam preheating coil, for example on line 22 ofFigure 1.

Figure 3 is a perspective view of the seam preheating coil.

Figure 4 is a transverse sectional view on line 4-4 of Figure 3,diagrammatically illustrating the magnetic field around the coilreaches, and also illustrating diagrammatically a can body side seamwithin the magnetic field of the elongated coil reach.

Figure 5 is a diagram giving one example of a high frequency generatorembodying the seam preheating coil of the present invention.

Preferences have been disclosed in the drawings and will be ratherspecifically described but attention is invited to the possibility ofmaking variations within the scope of the invention.

In Figure l a portion 10 of the arch of a can body maker is shown. Underthis arch, the can bodies are shaped into cylindrical form and theirside seams are bumped in the well known manner. Spaced from the usualstub horn 11 on which the shaped and bumped can bodies 12 are fed fromthe body maker 10 (by conven tional means), a solder applying means 13(forming no part of the present invention) has been shown. From the stubhorn 11 to and beyond the solder applying means 13, an outside horse,generally designated at 14, is illustrated. Operable longitudinally overthe horse 14 in the usual way, is a feeder chain 15 having the customaryfeeder lugs 16 which feed the can bodies 12 along the path defined bythe horse 14. Under and parallel with this path, the high frequency seampreheating coil 17 is mounted, said coil 17 being connected with a highfrequency generator 18 of any adequate form, one example beingdiagrammatically shown in Figure 5, later referred to.

Before proceeding to a detailed description of the coil 17, it will bewell to explain that the outside horse 14 should be of non-magneticmaterial in the region of the coil 17 to prevent it from interferingwith the magnetic field relied upon to heat the can seams 19. Forexample, the lower portion of the horse 14 may be formed by twochrome-plated can body supporting rails 20 of hard copper or bronze(Figure 2). Guide rods 21 may constitute the upper portion of the horse.

The coil 17 is formed from copper tubing of about diameter and receivescooling water in the usual way. This coil comprises an elongatedrectilinear reach 22, two return bends 23, two relatively short alignedreaches 24, disposed in parallel spaced relation to the reach 22, andtwo terminal portions 25, said reaches, return bends and terminalportions preferably being dimensioned and relatively placed as follows.The elongated reach 22 is about 6 in length; the return bends 23 are atthe ends of this reach 22; the aligned reaches 24 extend inwardly fromsaid return bends 25 and their longitudinal centers parallel and arespaced about 2 /2" from the longitudinal center of the elongated reach22, and the terminal portions 25 which connect with the generator 18 arelaterally bent from the inner ends of said aligned reaches 24 and extendaway from the elongated 3 reach 22. All of the elements 22, 23, 24 and2.5 lie in a single horizontal plane in the present disclosure.

The elongated rectilinear reach 22 is disposed longitudinally of the canbody feed path and in close proximity to the side seams 19, which seamsare in longitudinal alignment as the can bodies 12 leave the body makerand are maintained in this alignment as the bodies travel along thehorse 14. In the resent disclosure, the seams 19 are at the lower sidesof the can bodies 12 and therefore the elongated coil reach 22 is underthe path along which said bodies are fed and guided.

When the generator 13 is in operation, the elongated reach 22 createstubular magnetic field 26 (Figure 4) around itself, said field beingcomposed of concentric cir- .cular lines of force 27. The body sideseams 19 are maintained in this magnetic field 26 throughout theirtravel over the reach 22, and it is the action of this field which heatsthe seams 19. The heating energy is thus concentrated and localized onthe seam portions of the can bodies and is not wasted on large adjacentportions of said bodies. It is to accomplish this, that tubing of theparticular form and placement herein disclosed is employed.

During creation of the field 26, a similar field 28 (Figure 4) iscreated around each of the relatively short coil reaches 24 but thesefields 28 are not utilized in the heating of the cans.

The coil 17 may be mounted in any suitable manner. A horizontallyelongated flat support is shown and this support may be of anyappropriate insulating material, wood for example. The upper side of thesupport 29 is grooved at 29a for reception of the coil 17 andsurrounding insulating means. This insulating means may consist ofinsulating varnish and mica tape 31. The coil, thus shielded, is securedin the grooves 2% by cement 32.

Operation With the high frequency generator 1% in operation and itsoutput properly regulated, the coil reach 22 creates the tubularmagnetic field 26 which surrounds and extends from end to end of saidreach The can bodies 12 are fed along the horse M by the feeder chainlugs 16 and the side seams are maintained in alignment directly over thecoil reach 22. Thus during the entire travel of the can bodies over coilll, the seams 19 cut through the magnetic field 26 and the circularlines of force 217 travel transversely through said seams 19. The actionof this field thus very rapidly and intensively heats the seams andheating is concentrated and localized on the seam portions of the canbodies.

When using 300 amperes, 22% volts and a frequency of 450 kilocycles inthe coil itself and feeding the can bodies .12 at the rate of 600 perminute, it has been possible to continuously heat the side seams 19 toa' degree entirely adequate to prepare said seams for highly efficientsolder bonding. In attaining these results, a stand ard Westinghouseradio frequency generator (induction heater) has been used, including arheostat for varying the energy output of the coil 17, making itpossible to vary the temperature to which the seams will be heated. InFigure 1, a control knob for the rheostat of the generator 18, is shownat 33.

Any suitable high frequency generator may, of course, be employed andFigure 5 diagrammatically illustrates such a generator and the coil 17.As this generator is well known, it will sufiice to merely identify itsprincipal elements as follows:

34Conductor to high voltage rectifier.

35-Plate by-pass capacitor.

36Oscillator tube.

37--Filament by-pass capacitor.

38-Conductor to filament terminal board. 39-Conductor to grid resistors.

40Conducto r to ground on filament terminal board.

4 41-P1ate choke. 42-Plate blocking capacitor. 43Tank capacitor. 44-Tankcoil. 45-Stabilizer resistor. 46-Grid coil. 47--Grid by-pass capacitor.48Cooling water inlet. 49Cooling water outlet.

From the foregoing, it will be seen that novel and advantageousprovision has been made for carrying out the desired end. However,attention is again directed to the fact that variations may be made inthe example method and apparatus disclosures herein without departingfrom the spirit and scope of the invention as defined in the appendedclaims.

I claim:

1. In a can body side seam heating means, means for longitudinallyfeeding and guiding the can bodies along a predetermined path inlongitudinally spaced relation and with their side seams in alignment,at high frequency coil having an elongated reach directly centered alongthe aligned side seams and having a length greater than the combinedlength of a plurality of the can bodies and which creates a tubularmagnetic field around itself, said elongated coil reach being disposedunidirectionally with said path and being transversely spaced from saidpath, and means mounting said elongated coil reach in such position thatthe can body scams will travel longitudinally through said tubularmagnetic field as the can bodies travel along said path, and saidguiding and feeding means being constructed to feed the can bodies alonga rectilinear path, said elongated coil reach being rectilinear andparallel with said path, said guiding and feeding means and saidelongated rectilinear coil reach being so related as to dispose the canbody seams in close proximity to but spaced slightly from said elongatedrectilinear coil reach during travel of the can bodies along saidrectilinear path.

2. A structure as specified in claim 1; said high frequency coilcomprising said elongated reach in rectilinear form, return bends at theends of said elongated rectilinear reach respectively and disposed inthe same plane, relatively short aligned reaches extending inwardlytoward each other from said return bends respectively and spacedlaterally from said elongated rectilinear reach and terminal portionsbent laterally from the inner ends of said relatively short reaches andextending away from said elongated rectilinear reach; said coil beingformed from copper tubing of about in diameter, said elongatedrecti-linear reach being substantially 6' long and having itslongitudinal center parallel and spaced about 2 /2 from the longitudinalcenter of said relatively short reaches.

3. A structure as specified in claim 1; said high frequency coilcomprising said elongated reach in rectilinear form, return bends at theends of said elongated rectilinear reach respectively and disposed inthe same plane, relatively short aligned reaches extending inwardlytoward each other from said return bends respectively and spacedlaterally from said elongated rectilinear reach and terminal portionsbent laterally from the inner ends of said relatively short reaches andextending away from said elongated rectilinear reach; said mountingmeans comprising an elongated insulating base having grooves in whichsaid elongated rectilinear reach and said relatively short reaches areconfined.

lengths of, a plurality of can bodies and which creates a tubularmagnetic field around itself; the steps otaligning the side seams of thecan bodies, longitudinally feeding the can bodies in longitudinallyspaced relation on a path parallel with and transversely spaced fromsaid elongated rectilinear coil reach and directly centered along saidreach, and maintaining the aligned seams within said tubular magneticfield and in closely spaced proximity to said elongated rectilinear coilreach during travel of the can bodies along said path.

References Cited in the file of this patent UNITED STATES PATENTS

